Conductive Polymer/Transition Metal Oxide Hybrid Materials for Lithium Batteries
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Conductive Polymer/Transition Metal Oxide Hybrid Materials for Lithium Batteries Chai-Won Kwon1, Armel Poquet1, Stéphane Mornet1, Guy Campet1, Josik Portier1, A. Vadivel Murugan2, B. B. Kale2, K. Vijayamohanan3 and Jin-Ho Choy4 1 Institut de Chimie de la Matière Condensée de Bordeaux, 87 av. A. Schweitzer, 33608 Pessac Cedex, France 2 Center for Materials for Electronics Technology, Ministry of Information Technology, Govt. of India, Panchwati, Pashan Road, Pune 411 008, India 3 National Chemical Laboratory, CSIR, Pashan Road, Pune 411 008, India 4 National Nanohybrid Materials Laboratory, School of Chemistry, Seoul National University, Seoul 151-747, South Korea ABSTRACT Organic-inorganic hybrid materials were synthesized for use of lithium battery electrode by two strategies: 1) core-shell strategy for tri-dimensional transition metal oxide and 2) intercalation strategy for bi-dimensional (lamellar) transition metal oxide. We choose conductive polymers as an organic component for high electric conductivity and 3d-transition metal oxides as an inorganic counterpart for large capacity and processibility. Polypyrrole/maghemite and poly(3,4-ethylenedioxythiophene) (PEDOT)/vanadium pentoxide hybrids will be presented and compared with their pristine materials for core-shell and intercalation strategies, respectively. Polypyrrole/maghemite showed an enhanced electrochemical reversibility and capacity up to ~270 mAh/g in the potential range between 1.3 and 4.3 V vs. Li at 8 mA/g. PEDOT/vanadium pentoxide also exhibited improved reversibility and capacity up to ~330 mAh/g at 15 mA/g between 2.0 ~ 4.4 V vs. Li on the second discharge. XRD, IR, electron microscopy, XPS and Xray absorption spectroscopy were used to characterize the samples, and to examine oxidation state of the transition metals, doping character of the polymer and the nature of interaction between the polymer and the transition metal oxides.
INTRODUCTION The rapid development of modern electronic technology creates a strong demand for portable power sources. For example, popular portable electronic devices such as notebook computers, camcorders and cellular phones require small, but efficient and reliable batteries. Lithium batteries are considered to be the best choice, as they provide high output power and moderate lifetime. Generally, the lithium batteries are composed of cathode, anode, electrolyte, separator and packaging unit. Especially, electrode materials are of strong importance, because the capacity is mostly limited by the electrode materials. Traditional electrode materials are based on the redox potential difference of the electrode in the course of intercalation / deintercalation reactions. They are generally well-crystalline host compounds either with layered structure such as graphite, LiCoO2 and LiNiO2, or with tunnel structure like LiMn2O4. For the last decade, much effort has been made to improve the performance of the electrode materials. But, conventional synthetic methods are always restricted by the electrode material itself, and it
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